May 24 1978
From The Space Library
MSFC reported it had successfully conducted a first major test firing of the three Space Shuttle main engines during a 15sec run at the Natl. Space Technology Laboratories in Bay St. Louis. MSFC had already successfully fired one of the modified engines for 520sec at 100% thrust, more power than needed for the first Shuttle mission. Test results would aid in establishing countdown procedures. More than 300 contractor and NASA employees had worked on the test series, described by, program officials as the most complex large propulsion-system evaluation undertaken in the U.S. space program. Test budget for firings and facilities was $52 million.
Main propulsion-test articles were the Martin Marietta external tank containing propellant for firing tests, just as it would during Shuttle missions; the Rockwell International orbiter simulator; three Rocketdyne main engines; and the Rockwell International shuttle avionics test set, replacing the Shuttle-orbiter computers during tests. Key Shuttle launch and flight parameters to be verified by propulsion-test data were the cryogenic boiloff rate of external-tank propellants on the launch pad; rate of external tank self-pressurization; engine-prestart requirements, such as pressure and temperature milestones; starting, throttling, and cutting off the engine, using external-tank propellants with the engines operating in close proximity; engine gimbaling; control-system response; loads placed by the engines on the orbiter; and launch acoustic data. Flight-dynamics engineers had been especially interested in verifying control-system models with the main propulsion-test data.
Test 1, scheduled for 2.35sec, had been terminated at 1sec because of an instrument problem. Test 2, scheduled for 15sec with the engines at 70% thrust, would assess propellant-flow paths from the tank through the orbiter and into the engines under thrust conditions. Test 3, planned for 15sec at 90% thrust level, would reverify overall propellant-system operation, and effect of the engine plumes on the test stand's flame deflector. Test 4, planned for 40sec at 90% thrust, would define propellant flow and flame-deflector hot spots. Firings 5 through 7, lasting 500 to 600sec, would duplicate Shuttle flight profiles; firings 8 through 10 would run for long durations with flight-rated 77:1 nozzles; and firings 9 through 13 would have the 35:1 nozzles reaffixed for engine throttling, to demonstrate the effect on flight profiles.
Although the main engine had taken the blame for Shuttle launch-date slip, the external tank and solid-fuel rocket booster tests also had failed to support a March launch. (Marshall Star, May 24/78, 1, May 17/78, 1; JSC Roundup, May 12/78, 1; Av Wk, May 22/78, 55; May 29/78, 49)
NASA announced that, as interrogations from tracking stations in Mar. and Apr. had successfully made contact with Skylab, the agency would begin in early June to uplink from JSC mission control a series of Skylab attitude-change procedures to put a new program into Skylab's onboard computer. The attitude-control system would be used to maneuver the spacecraft into the desired position and operate the control-moment gyros to keep it there. The procedures establishing control of Skylab, to be completed by mid-June, might extend its orbital lifetime by 6 to 12mo. The attitude change, if successful (and if the gyros continued to operate), could delay Skylab's reentry into the atmosphere until late 1979 or mid-1980. The maneuvers would decrease atmospheric drag on the spacecraft by aligning it with the flight path; once in the desired attitude, Skylab could survive from day to day without further maneuvers or adjustments. (JSC Release 78-20; JSC Roundup, May 26/78, 1; Marshall Star, May 24/78, 1)
MSFC reported that a patent had been issued for a reel mechanism and associated control system invented by MSFC employees Ralph Kissel and Charles Rupp for the Shuttle tethered satellite system (TSS). NASA had considered the TSS as a means of enhancing Space Shuttle performance of scientific investigations and operational activities in space. The system would use a flexible tether line to deploy and retrieve subsatellites at distances as great as 100km from the orbiter. NASA had judged the mechanism and control-system invention would contribute significantly to overall feasibility of the TSS concept. (Marshall Star, May 24/78, 4) May 25: NASA announced that HEAO 1, first of a series of observatories designed to study celestial x-rays and gamma rays, was officially a success. Primary objective of HEAO 1 was to obtain highly detailed experimental data on astrophysical phenomena by measuring sizes and locations of x-ray sources and determining their intensity and time variation; according to Dr. Noel Hinners, NASA associate administrator for space science, the objective had been accomplished. NASA had authorized an extension of HEAO 1's mission to a second scan of the celestial sphere, and would broaden scientific participation through a guest-investigator program. NASA planned to launch in Nov. 1978 a second high-energy astronomy observatory designed for detailed study of interesting sources pinpointed by HEAO 1; a third would be launched in 1979. (NASA Release 78-80)
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